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Ether Calc EtherCalc is a web spreadsheet. Your data is saved on the web, and people can edit the same document at the same time. Best free dating script node js multiple chat rooms changes are instantly reflected on all screens. Please download and install Node. If a Redis service is running on the same host, EtherCalc will prefer it over file-based storage to improve performance. Installation instructions on the Sandstorm platform is available here. We also provide a Docker package.
EtherCalc can be installed on a Cloudron using the EtherCalc app. If you would like to purchase the bookall royalties will be donated to Amnesty International.
The history of spreadsheets spans more than 30 years. The first spreadsheet program, VisiCalc, was conceived by Dan Bricklin Best free dating script node js multiple chat rooms and shipped in The original concept was quite straightforward: Formulas are composed of normal arithmetic operators Best free dating script node js multiple chat rooms various built-in functions, and each formula can use the current contents of other cells as values.
Although the metaphor was simple, it had many applications: The possibilities were practically ropms. All these uses made VisiCalc into the first "killer app" of the personal computer era.
In the decades that followed successors like Lotus and Excel made incremental improvements, but the core metaphor stayed the same. Most spreadsheets were stored as on-disk files, and loaded into memory when opened for editing. Collaboration was particularly hard under the file-based model:. Fortunately, a new collaboration model emerged to address these issues with elegant simplicity. It is the wiki model, invented by Ward Cunningham inand popularized by Wikipedia in the early s.
Instead of files, the wiki mutliple features server-hosted pages, editable in the browser without requiring special software.
Those hypertext pages can easily link to each other, and even include portions of other pages to form a larger page. All participants view and edit the latest version by default, with revision history automatically managed by the server. Inspired by the wiki model, Best free dating script node js multiple chat rooms Bricklin started working on WikiCalc in It aims to combine the authoring ease and multi-person editing of wikis with the familiar visual formatting and calculating metaphor of spreadsheets.
The first version of WikiCalc had several features that set it apart from other spreadsheets at the time:. The ability to compose a master spreadsheet from several smaller spreadsheets proved particularly handy. For example, imagine a How online dating is bad How PLM is Being Applied to Support Todays Enterprises where each salesperson keeps numbers in a spreadsheet page.
Each sales manager then rolls up their reps' numbers into a regional spreadsheet, and Free dating chat in nigeria Product Complexity, Digital Transformation, and the Innovation Imperativ VP of sales then rolls up the regional numbers into a top-level spreadsheet.
Each time one of the individual Australian dating apps for iphone is updated, all the roll-up spreadsheets can reflect the update. If someone wants further detail, they simply click through to view the spreadsheet behind the spreadsheet. This roll-up capability eliminates the redundant and error-prone effort of updating numbers in multiple places, and ensures all views of the information stay fresh.
To ensure the recalculations are up-to-date, WikiCalc adopted a thin-client design, keeping all the state information on the server side. Unsurprisingly, this design depends on a fast connection between the browser and the server. When the latency is high, users will start to notice the frequent appearance of "Loading…" messages freee updating a cell and seeing its new contents as shown below.
This is especially a problem for users interactively editing formulas by tweaking the input and expecting to see results in real time. Due to these shortcomings, while WikiCalc was useful as a stand-alone server running on localhost, it was not very practical to embed as part of web-based content management systems. This rewrite was aimed at large, distributed collaborations, and sought to deliver a look and feel more like that of a desktop app.
It contains a dictionary from coordinates to Cell objects, each representing a single cell. Empty cells need no entries, and hence consume no memory at all. As it receives view events such as scrolling and resizing, it updates its associated RenderContext object. As it receives update events that affects the sheet's content, it schedules new commands to the sheet's command queue. All symbols are placed under the SocialCalc. Each update on the sheet Best free dating script node js multiple chat rooms through the ScheduleSheetCommands method, which takes a command string representing the edit.
The application embedding SocialCalc may define extra commands on their own, by adding named callbacks into the SocialCalc. CmdExtensionCallbacks object, and use the startcmdextension command to invoke them. Some common commands are shown below:. Applciations embedding SocialCalc may define extra commands on their own, by adding named callbacks into the SocialCalc.
To improve responsiveness, SocialCalc performs all recalculation and DOM updates in the background, so the user can keep making changes to several cells while the engine catches up on earlier changes in the command queue. When a command is running, the TableEditor eating sets its busy flag to true; subsequent commands mode then pushed into the deferredCommands queue, ensuring a sequential order of execution.
The event scri;t looks like this:. As the diagram shows, the Sheet object keeps sending Bedt events to notify the user of the current state of command execution, through each of the four steps:. Sends cmdstart upon start, and cmdend when the command finishes execution. Otherwise, if the command changed the visual appearance of one or more on-screen cells, enter the Render step. If neither of the above applies for example with the copy commandskip to the PositionCalculations step.
Sends calcstart upon start, calcorder every ms when checking the dependency chain of cells, calccheckdone when the check finishes, and calcfinished when all affected cells received their re-calculated values. Sends schedposcalc upon start, and doneposcalc after updating Best free dating script node js multiple chat rooms scrollbars, the current editable cell cursor, and other visual components of the TableEditor.
Because all commands are saved as they are executed, we naturally get an audit log of all operations. CreateAuditString method multipld a newline-delimited string as the audit trail, with each command in a single line. ExecuteSheetCommand also creates an undo command for each command it executes. For example, if the cell A1 contains "Foo" and the user executes set A1 text Barthen an undo-command set A1 text Foo is pushed to the undo stack. If the user clicks Undo, then the undo-command is executed to restore A1 to its original value.
Now let's look at the TableEditor layer. The view layer, handled by the RenderContext class, also differs from WikiCalc's design. Because RenderContext only renders the visible region, Best free dating script node js multiple chat rooms size of Sheet object can be arbitrarily large without affecting its performance.
The input box is managed by two Free chat line room numbers good opening messages on dating websites The former manages the above-the-grid edit row, while the latter shows an updated-as-you-type preview layer, overlaying the ECell's content:.
Usually, the SocialCalc engine only needs tooms communicate to the server when opening a spreadsheet for edit, and when saving it back to server. For this purpose, the Sheet.
ParseSheetSave method parses a save format string into a Sheet object, and the Sheet. CreateSheetSave method serializes a Sheet object back into the save format. Formulas may refer to values from any remote spreadsheet with a URL. The recalc command re-fetches the externally referenced spreadsheets, parses them again with Sheet. ParseSheetSaveand stores them in a cache so the user can refer to other cells in the same remote spreadsheets without nnode its content. This format is designed to Celebs Go Dating: Top 10 Moments human-readable, as well as being relatively easy scripr generate programmatically.
This makes it possible ropms Drupal's Sheetnode plugin to use PHP to convert between this format and other popular spreadsheet formats, such as Excel. Now that we have a good idea about how the pieces in SocialCalc fit together, let's look at two real-world examples of extending SocialCalc. The first example we'll look at is enhancing SocialCalc's text multipl with wiki markup to display its rich-text rendering right in the table editor:.
We added this feature to SocialCalc right after its 1. Since Socialtext already has an open-source wiki platform, it was natural to re-use the syntax for SocialCalc as well. To implement this, we need a custom renderer for the textvalueformat of text-wikiand to change the default format for text cells to use it.
In SocialCalc, each cell has a datatype and a valuetype. It does so by inspecting each cell's valuetype: If it begins with t, then the cell's textvalueformat attribute determines how generation is done. If it begins with nthen Beest nontextvalueformat attribute is used instead. However, if the cell's textvalueformat or nontextvalueformat attribute is not defined explicitly, then a default format is looked up from its valuetypeas shown below:.
Support for the text-wiki value format is coded in SocialCalc. This is the recommended style throughout the SocialCalc codebase; it improves modularity by making it possible to plug in different ways of expanding wikitext, as well as keeping compatibility with embedders sdript do not desire this feature.
The final step involves scheduling the set sheet defaulttextvalueformat text-wiki command right after the spreadsheet initializes:. The next example we'll explore is multi-user, real-time editing on a shared spreadsheet.
This may seem complicated at first, but thanks to SocialCalc's modular design all it takes is for each on-line user to broadcast their commands to other participants. To distinguish between locally-issued commands and remote commands, we add an isRemote parameter to the ScheduleSheetCommands method:.
Now all we need to do is to define a suitable SocialCalc.